1. Field of the Invention
The present invention relates generally to cleansers, and more particularly to those cleansers that include oxidizing and bleaching agents.
2. Description of the Prior Art
Cleanser compositions have for some time used oxidizing agents and bleaching agents in concert to remove visible stains from hard surfaces, while at the same time effecting the removal of scale or plaque build-up on those surfaces. Thus, cleaning compositions, prepared with abrasive materials for use as scouring cleansers, or alone for purpose of mild surface cleaning applications, have employed a variety of sulfate salts, eg. bisulfates, monopersulfates, and sulfates as detergents, oxidizers and the like, and have utilized alkali metal and alkaline earth metal halides as bleaches.
U.S. Pat No. 3,458,446 to Diaz discloses an abrasive cleansing composition that utilizes certain monopersulfate oxidizing agents in combination with a water-soluble bromide salt, in place of chlorine-liberating constituents conventionally employed in such compositions. The replacement of the chloride constituents by the bromide constituents was found to eliminate the unpleasant odor of chlorine. The composition disclosed in Diaz was primarily intended for use in powdered form, and utilized a variety of additives, such as detergents, builders and the like in its formulation.
The preparation of cleansers to be utilized in a solution for dipping, or soaking the articles to be cleaned therein, presents different problems from those that attend the preparation and use of cleansing compositions that are applied to the surface of the articles to be cleaned. Thus, whereas one may apply a composition, either in liquid or granular form, to a surface and may then agitate the surface to assist the cleaning operation, the employment of compositions that operate in a "passive" manner to serve as dipping solutions and the like, gives no indication of their efficacy, and of the period of their activity. In particular, cleansers utilized for the preparation of dipping solutions for dentures and the like, have conventionally exhibited an effervescent action in solution that assists in stain and plaque removal by providing a desired amount of agitation in the solution to promote cleansing activity. Also, such compositions have conventionally included colorants such as dyes, incorporated into the composition to indicate the presence of the cleansing composition in the solution.
The effervescent activity of these solution-forming cleansing compositions has conventionally been provided by the inclusion in the composition of the ingredients sodium bicarbonate and citric acid. Correspondingly, the reaction of these two ingredients has taken place at a pH that is weakly acidic or neutral, with a sacrifice in the efficiency and speed of cleaning, that would be achieved by the employment of a composition operable at a more basic pH.
The employment of the colorant in the composition as an indicator has been for the purpose of not only indicating the presence and activity of the cleansing composition, but serves to indicate by its disappearance the cessation of cleaning activity. For example, in the instance where denture cleansers are prepared, a dye component is included as an indicator to signify by coloration the presence of the cleansing composition and the commencement of its activity. In these applications, the actual period of activity is reasonably finite, and is predetermined by the manufacturer.
Accordingly, as the indicator or dye signals the user that the cleaning process has ended, attempts have been made to control the disappearance or fading of the dye, so that the disappearance of the dye will coincide with the completion of the cleaning cycle. Attempts to control the time span of the dye component have included the addition of limited quantities of dye, and the inclusion of additional amounts of bleaching agents to cause the dye to fade more quickly. The first approach has been generally unsuccessful, and the second approach proved uneconomical; the inclusion of additional bleach to fade the dye frequently required additional dye to be added to the composition to give the appropriate depth of initial coloration, and in turn required additional bleach to be added for fade control.
The present invention is believed to provide solutions to the aforementioned problem.